I've been on a local search for the stuff for about a week now for my next project. I've got a buddy in the landscaping business helping me out, so if I find something I'll let you know. I'm thinking at least one of the local nurseries should have it or be able to get it.
Just do a search for hydroponic stores in your city (i.e. google "hydroponics Chicago" if you live in chicago). These stores are popping up everywhere. I found a hydroponics store (actually 3 of them) less than 10 minutes from me. The cost is the same as online, you just don't have to pay shipping (which is usually $20+). Also, these hydroponic stores sell ballasts, bulbs, etc. which are comparable in price but you don't have to pay shipping.